/**
 * Copyright 2010 Eric Taix Licensed under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with the
 * License. You may obtain a copy of the License at
 * http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable
 * law or agreed to in writing, software distributed under the License is
 * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 */
package org.jared.synodroid.common;

/**
 * An utility class which displays a EULA Big thanks to Konstantin
 * (http://androiddevstudio.com/) who's created a tutorial for this class
 * and saved me a lot of time.
 * 
 * @author Eric Taix (eric.taix at gmail.com)
 */

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.SharedPreferences;

import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.Closeable;

import org.jared.synodroid.ds.R;

/**
 * Displays an EULA ("End User License Agreement") that the user has to accept before using the application. Your application should call {@link Eula#show(android.app.Activity)} in the onCreate() method of the first activity. If the user accepts the EULA, it will never be shown again. If the user refuses, {@link android.app.Activity#finish()} is invoked on your activity.
 */
public class Eula {
	private static final String ASSET_EULA = "EULA";
	private static final String PREFERENCE_EULA_ACCEPTED = "eula.accepted";
	private static final String PREFERENCES_EULA = "eula";

	/**
	 * callback to let the activity know when the user has accepted the EULA.
	 */
	public interface OnEulaAgreedTo {

		/**
		 * Called when the user has accepted the eula and the dialog closes.
		 */
		void onEulaAgreedTo();
	}

	/**
	 * Displays the EULA if necessary. This method should be called from the onCreate() method of your main Activity.
	 * 
	 * @param activity
	 *            The Activity to finish if the user rejects the EULA.
	 * @return Whether the user has agreed already.
	 */
	public static boolean show(final Activity activity, boolean forceToShow) {
		final SharedPreferences preferences = activity.getSharedPreferences(PREFERENCES_EULA, Activity.MODE_PRIVATE);
		if (!preferences.getBoolean(PREFERENCE_EULA_ACCEPTED, false) || forceToShow) {
			final AlertDialog.Builder builder = new AlertDialog.Builder(activity);
			builder.setTitle(R.string.eula_title);
			builder.setCancelable(!forceToShow);
			if (!forceToShow) {
				builder.setPositiveButton(R.string.eula_accept, new DialogInterface.OnClickListener() {
					public void onClick(DialogInterface dialog, int which) {
						accept(preferences);
						if (activity instanceof OnEulaAgreedTo) {
							((OnEulaAgreedTo) activity).onEulaAgreedTo();
						}
					}
				});
				builder.setNegativeButton(R.string.eula_refuse, new DialogInterface.OnClickListener() {
					public void onClick(DialogInterface dialog, int which) {
						refuse(preferences, activity);
					}
				});
				builder.setOnCancelListener(new DialogInterface.OnCancelListener() {
					public void onCancel(DialogInterface dialog) {
						refuse(preferences, activity);
					}
				});
			} else {
				builder.setPositiveButton(R.string.eula_hide, new DialogInterface.OnClickListener() {
					public void onClick(DialogInterface dialog, int which) {
						// DO NOTHING JUST HIDE IT ...
					}
				});
				builder.setOnCancelListener(new DialogInterface.OnCancelListener() {
					public void onCancel(DialogInterface dialog) {
						// DO NOTHING JUST HIDE IT ...
					}
				});
			}
			builder.setMessage(readEula(activity));
			builder.create().show();
			return false;
		}
		return true;
	}

	private static void accept(SharedPreferences preferences) {
		preferences.edit().putBoolean(PREFERENCE_EULA_ACCEPTED, true).commit();
	}

	private static void refuse(SharedPreferences preferences, Activity activity) {
		preferences.edit().putBoolean(PREFERENCE_EULA_ACCEPTED, false).commit();
		activity.finish();
	}

	private static CharSequence readEula(Activity activity) {
		BufferedReader in = null;
		try {
			in = new BufferedReader(new InputStreamReader(activity.getAssets().open(ASSET_EULA)));
			String line;
			StringBuilder buffer = new StringBuilder();
			while ((line = in.readLine()) != null)
				buffer.append(line).append('\n');
			return buffer;
		} catch (IOException e) {
			return "";
		} finally {
			closeStream(in);
		}
	}

	/**
	 * Closes the specified stream.
	 * 
	 * @param stream
	 *            The stream to close.
	 */
	private static void closeStream(Closeable stream) {
		if (stream != null) {
			try {
				stream.close();
			} catch (IOException e) {
				// Ignore
			}
		}
	}
}
